Farmall Cub

Ok, My Cub is a 53 with positive ground. The one my buddy bought is a 62 with negative ground. I'm not sure I understand the reason for the positive ground. Can someone give me a short lesson in the reasons for positive ground? I've searched this site but didn't find an answer. Thanks

I don't have the official reason butt I can tell you electrically its makes no difference. Possibly 50yrs ago the standard hadn't been set yet. I think some cars were even pos. grounded back then. Just like any techology in its infancy not everyone aggreed on which way to do it until sometime in the 50's. I'd too would be curious to here some of the replys to this to see what made the industry standardize to neg. gnd. Of course the obvious is for safety and protect equipment from being damaged from improper connections. Electron theory says pos. gnd is actually more correct butt its easier to think in terms the other way around.

In reality, either way works just fine. The original 6 volt systems in automobiles were positive ground. There was supposed to be a benefit as far as corrosion of terminals or some similar reason for positive ground. To this day, I've yet to see any definite proof that one way was better than the other. When systems went to 12 volts, they switched to negative ground. I suspect the debate about which way current flows from a battery had a lot to do with it. Some experts theorized current flow was from negative to positive and some theorize the flow was positive to negative. Either way, as long as the system is connected as designed, it should work OK. Even if the older 6 volt systems are reversed, they will work as long as the generator is re-polarized to charge with the opposite polarity and the ammeter is reversed.

Since an electron carries a negative charge, the current flow is from negative to positive. The coil doesn't care which direction the electrons flow but the points do. Since the coil connection determines the flow through the points, it should be connected the same as the battery. Naturally, a magneto doesn't care at all.

George, I agree with you. But I've heard theories on "hole" flow vs. "electron" flow (although it's been a few years and I probably don't remember much) and it gets a lot of arguments started between engineers and technical people. As you said, the components don't care which direction the flow is in, it's the fact that it flows that counts. Unfortunately, modern electronic equipment does care. (ruined my share of transistors a number of years ago)

Ok, I've learned something new today.....Thanks guys.

George- It should be pointed out that the points themselves don't care which way current flows but the condenser does and that is what technically breaks current flow in the primary windings.

I'm gonna disagree with both of you. The points are a switch and polarity is irrelevant. The condensor is not an electrolytic so it doesn't care what the polarity is either. The coil, should also not be polarity sensitive, but appears from a practical standpoint, to be somewhat sensitive to how it is in the circuit. The coil secondary will produce a high voltage that will either arc from the center electrode of the plug to the leg or vice-versa. That may affect plug life, but not significantly.

I'm going to have to agree with Bigdog on this one. If the cap (condenser) was electrolytic then it would be a problem but reversing the leads would fix it as electrolyic caps have + and - leads. The points are nothing but a switch.

I also agree with George that's why I have 3 Cubs and 5 magnetos.

Now you guys are trying to confuse me! I better leave it the way it is Thanks.

Maybe it's just an old wives' tale, but many say incorrect coil polarity will shorten point life.

I really can't say why this should be true. Could it be because of which side of the points the condenser (paper capacitor) is on?

I learned about electron flow in 7th grade science, in 1946. I never heard of "hole" flow.

I believe it was my high-school mechanics teacher that told me that incorrect coil polarity would shorten the life of the coil. I guess that theorys are like bottoms,,, every ones got one!!

I've never heard of "hole flow" either (whole?) .

Hole flow is a theory that was subscribed to by some electrical engineers. Supposedly the movement of electrons left a "hole" that was then filled by the next electron etc. Most looked at it as electron flow from negative to positive. Some said it was hole flow from positive to negative.
When I was in electronics tech school in the 60's we were taught about electron flow and warned about the crazy engineers who believed in hole flow.

It's all clear now. It's like the electrons are driving on a freeway. Just like real life, when they allow a safe "hole" from the electron ahead, another electron gets in it. How'm I doin'?

You got it Granddad!